Cub Cadet MTD 70 Series - Manual (Page 96)

61, 65 and 70 Series Vertical Shaft Engines
90
NOTE: Intermittent failure requires tests for voltage
and resistance to be made when the engine
is cold, and again when it is hot. Typical cus-
tomer complaint: “It stops after I mow for 10
minutes and I can’t get it to re-start”.
• To confirm that the problem is ignition-based, it
is necessary to “catch it in the act”.
• Resistance normally increases slightly as tem-
perature increases.
NOTE: Failure of the magnets in the flywheel is
exceedingly rare. To test the magnets, sim-
ply hold an item made of ferrous metal
roughly 1/4” (.635cm) away from the mag-
nets in the flywheel. It should be drawn to
the flywheel. A wrench or screwdriver is suit-
able for this test.
NOTE: An inexpensive compass or bar magnet can be used to confirm opposite polarity of the flywheel mag-
nets. See Figure 7.13.
11. Inspect the flywheel.
The flywheel is a frequently forgotten component of the ignition system. It holds the magnets that induce a field in
the module which in turn produces a spark. But it also controls the timing of the ignition system by controlling when
the magnets are introduced to the module.
A sheared flywheel key will throw off the ignition timing. To inspect the flywheel and key:
1. Remove the recoil assembly by following the steps describe in Chapter 6: Starter.
2. Remove the flywheel by following the steps described in the flywheel section of this chapter.
3. Inspect the flywheel key and the key way on the crank shaft.
NOTE: If the flywheel key is damaged, replace it. If the keyway on the crankshaft is damaged, the engine must
be short blocked.
Figure 7.13
Opposite poles of bar magnets
are attracted to opposite pole
flywheel magnets for the sake
of illustration